Beta-Ag2Te: A topological insulator with strong anisotropy

TL;DR

This paper provides evidence that beta-Ag2Te is a topological insulator with highly anisotropic surface states, demonstrated through first-principles calculations and quantum interference measurements in nanoribbons.

Contribution

It combines theoretical predictions with experimental transport measurements to confirm the topological insulator nature and anisotropic surface states of beta-Ag2Te.

Findings

Presence of topological surface states confirmed by quantum interference effects

Beta-Ag2Te exhibits strong anisotropy in its surface states

Coherent electron transport observed in nanoribbons

Abstract

We present evidence of topological surface states in beta-Ag2Te through first-principles calculations and periodic quantum interference effect in single crystalline nanoribbon. Our first-principles calculations show that beta-Ag2Te is a topological insulator with a gapless Dirac cone with strong anisotropy. To experimentally probe the topological surface state, we synthesized high quality beta-Ag2Te nanoribbons and performed electron transport measurements. The coexistence of pronounced Aharonov-Bohm oscillations and weak Altshuler-Aronov-Spivak oscillations clearly demonstrates coherent electron transport around the perimeter of beta-Ag2Te nanoribbon and therefore the existence of metallic surface states, which is further supported by the temperature dependence of resistivity for beta-Ag2Te nanoribbons with different cross section areas. Highly anisotropic topological surface state of beta-Ag2Te suggests that the material is a promising material for fundamental study and future spintronic devices.